The GIF Symposia are public scientific events aimed at disseminating the results of international collaborative research performed within the Forum. The first GIF Symposium was held in Paris, France in 2009, the second in San Diego, United States in 2012 and the third in Chiba, Japan in 2015. This fourth GIF Symposium, held in Paris on 16-17 October 2018, is designed to inform and educate audiences beyond the GIF community. Its objective is to report the achievements of the Forum in developing nuclear energy systems that are aligned with today’s global sustainable development goals. In particular, the fourth GIF Symposium outlines a credible GIF path towards achieving the goals of the updated GIF R&D Roadmap, leading to the demonstration and deployment of innovative nuclear energy systems that will establish nuclear energy as a valuable part of the global, long-term sustainable carbon-free energy mix.